Cumulative trauma disorders, caused by precipitated by or aggravated by repeated exertions or movement of the body, are prevalent in those persons who must perform repeated tasks for extended periods of time. The cumulative trauma disorders may be a muscular problem, such as myalgia, a tendon problem such as tendinitis or a nerve problem such as carpal tunnel syndrome.
The prior art has developed a number of chairs having movable seats, backs and arm rests. To reduce the conditions which may cause, precipitate or aggravate the cumulative trauma disorders.
Aaras et al, in U.S. Pat. No. 4,277,102, discloses a chair in which arm rests disposed on the opposite sides of the seat are adjustable in height, width and angle, by means of lockable universal joints. Stenvall, in U.S. Pat. No. 4,822,103, discloses an arm rest adjustable in a vertical and a horizontal direction while Tubler, in U.S. Pat. No. 4,884,846, discloses an arm rest for a chair adjustable in a vertical and transverse direction. Resin, in U.S. Pat. No. 4,887,866, discloses an adjustable arm rest connected between a seat and a reclinable back of a chair.
Wilson, in U.S. Pat. No. 5,135,190, discloses an articulating ergonomic support system for supporting separately the forearm and wrist of the occupant. The wrist support may be adjusted horizontally with respect to the forearm support and adjusted in a vertical direction by means of an eccentric. Althofer et al, in U.S. Pat. No. 5,143,422, discloses an adjustable active arm support which may be adjusted in the vertical and transverse directions and the arm rest itself may be rotated in a horizontal plane and tilted to fully support the occupants forearm. Finally, Bonutti, in U.S. Pat. No. 5,215,282, discloses an adjustable arm rest for a chair adjustable in a vertical direction, transverse direction, tiltable about a horizontal axis for optimum support of the forearm.
Although the prior art teaches arm rests which support the forearm and wrist of the chair's occupant, there are many known applications in which it is desirable to support both the upper arm as well as the forearm to reduce the occurrence of cumulative trauma disorders.